The ultimate goal of this project is to develop a DNA probe-based chemiluminescent homogeneous assay system for the rapid, simple and sensitive detection of infectious disease organisms in clinical samples. The hydrolysis and subsequent loss of chemiluminescence of the acridinium ester attached to a DNA probe has been shown to proceed at a substantially reduced rate when the probe is hybridized to its target nucleic acid as compared to the unhybridized probe. The specific aim of this application is to determine the optimal site of acridinium ester attachment with respect to nucleotide sequence and location within the oligomer to yield maximum hydrolysis rate differential between hybridized and unhybridized oligomer. These parameters will be studied in a series of defined-sequence oligonucleotides labeled with acridinium ester, using kinetic analysis of the hydrolysis event and determination of thermal stability of the hybrid complex. The data will be used to refine and optimize a chemiluminescent homogeneous assay system based on this differential hydrolysis rate phenomenon. Such an assay system should significantly improve the speed and simplicity with which infectious diseases are currently being diagnoses, and as such would be a commercially attractive product.